Every manufacturer is under pressure to save money. We hear it almost daily, and we get it. It’s crucial to remain competitive while maintaining good margins. To achieve this, buyers will look everywhere to cut costs. This includes injection molded components, where opting for the lowest bid can be tempting. But custom injection molding is more complex than simply installing a mold and pressing a button. It relies on many factors, all of which can introduce risk into the process. If a buying decision is driven solely by part price over process capability, initial savings can disappear quickly. Let’s look at some of the risk factors you may face when going with the lowest bidder:
Inconsistent Tolerances and Mold Shrinkage
Low-cost suppliers will often cut corners on Design for Manufacturability (DFM) reviews and mold thermal management. When skipping this critical upfront analysis or using cheaper mold steels, problems such as uneven cooling and resin shrinkage will happen. Parts warp, sink, and drift out of tolerance. If the supplier is paying attention, they wind up in the scrap bin. If not, they become your problem.
High Defects and Scrap Waste
To keep prices low, molders will often run aggressive cycle times to protect their thin margins. But rushing parts through production leads to defects such as flashing, short shots, internal voids, and others. And as the old saying goes, haste makes waste. Defective parts wind up getting scrapped. This slows production and usually leads to missed delivery dates.
Rapid Tool Wear and Added Maintenance
Making a quality, high-performing mold requires quality tool steel, precise machining and polishing. Lower quotes will often rely on inferior tooling made from soft aluminum or lower-grade steels that usually wear much quicker than expected. This leads to unplanned repairs bills and production halts. All of which are avoidable when corners aren’t cut.
Resin Inconsistencies and Surprise Substitutions
Material consistency is a major factor for achieving a successful run. It’s critical for more demanding parts such as those used in medical, aerospace, and other demanding applications. T0 maintain profit margins, some shops will take certain liberties with material sourcing.
Unacceptable Regrind Levels – regrinding runners and scrap parts is encouraged as it helps keep material costs in check and helps reduce carbon footprint. However, some suppliers will exceed standard ratios, which are often between 10-15%. The problem is that higher regrind ratios thermally degrade polymer chains. This weakens the parts impact resistance and structural integrity.
Unspecified Material Grades – rather than use the engineering-grade resin that is specified, low-cost molders might run a generic-equivalent or off-spec grade. While they might be chemically similar, cheaper alternatives tend to lack consistent flow rates, which can lead to undesired part quality variation.
Mixing Lots and Suppliers – to help keep resin prices low, some molders will buy short-lot surpluses or blend raw material from multiple secondary suppliers. Using inferior plastics or mixing different lots often leads to viscosity changes during production. The leads to issues such as inconsistent wall thickness, color banding, and unpredictable part shrinkage.
Conclusion
A low piece-price quote rarely translates to quality parts. While less forgiving applications may get away with inferior parts, demanding ones simply will not. Cutting corners to cut price usually leads to failed injection molding programs. Ultimately, chasing the lowest bid usually increases your total project cost. No savings earned. It costs you significantly more than partnering with a reliable molder from the start.
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